Automobile and truck accidents normally require that the overturned equipment be turned upright before it can be moved away. Conventional equipment presently in use comprises a pickup truck having a pivoted or fixed boom on the truckbed. Typically, this equipment is limited in height because it must pass beneath telephone wires, power lines, freeway overpasses and the like. Accordingly, the truck-mounted equipment can stand no more than about twelve or fourteen feet in height. Because it is limited in height, it is limited in the angle at which the hoist cable lifts equipment. The hoist cable is ordinarily rigged by means of a hook to the overturned vehicle. In righting an overturned vehicle of some size, the hoist cable does little lifting and all too often tends to drag the overturned vehicle toward the tow truck. This is not the most proficient manner of lifting and righting an overturned vehicle.
The foregoing approach is more than acceptable for light vehicles in the range of one or two tons. It is not very effective in righting an overturned trailer with a weight of perhaps twenty to thirty tons. As an example, consider a tractor pulling a trailer connected to it via a fifth wheel. Consider further the trailer loaded with several tons of pipe so that the trailer and cargo mounted thereon weigh twenty-five tons. A load of this magnitude is not uncommon. In the event the tractor and trailer overturn, the current procedure by which the trailer is righted is to utilize two or three tow trucks positioned so that their hoist cables, when extended, reach over the top of the overturned trailer and hook to the trailer on the far side from the tow trucks. The cables, once extended, partly wrap around the fallen trailer. The trailer is then righted by pulling with the hoist cables. This pull is exerted almost parallel to the surface on which trailer rests because the tow trucks are constrained in height. Some skidding may occur as the trailer is pulled by the hoist cables toward the tow trucks. Eventually, it will roll, and, in so doing, it will roll toward an upright position. Eventually, the trailer is restored to an upright position. Restoration of the upright position requires that the trailer be located on a surface sufficiently firm to hold the trailer against unlimited skidding and further requires that the trailer withstand the twisting that results from the steps taken to upright it.
It is not uncommon for an overturned trailer to block traffic for upwards of two or three hours, while two or three tow trucks are located. Moreover, there is a severe limitation on the operative deployment of the tow trucks. That is to say, if the trailer has overturned on the shoulder of a major thoroughfare, it is almost essential in most circumstances that the tow trucks be located on the pavement to pull the trailer back toward the pavement in the act of uprighting it. This places the several tow trucks on the pavement in a position which inevitably must block traffic flow. When traffic is blocked, substantial police work is required to redirect traffic for the duration of the accident. This is expensive and very aggravating to the public.